In the (rare) event of a left-handed QB, does this mean the OTs switch sides (i.e. left tackle on the right) so that the best tackle is still protecting the QB's blind side? Or would the Defense's best pass rusher still come at the QB from the QB's left-hand side as per normal?

This is quite an interesting question, to which I don't know the definitive answer. I would suspect everything would swap sides, so the best tackle would defend the blindside of the QB, and the best DL would attack this side.

If a team has a left handed quarterback as a starter then the tackle with the best pass pro would be at right tackle rather than left. An example of this is Hall of Fame tackle Anthony Munoz who while playing right tackle for Cincinnatti protected left handed QB Boomer Esiason's blindside.

You wouldnt see the line flipping sides if a backup came in during a game - left handed QBs are quite rare and you would probably only see an alignment change if the right handed starter was out for a few games.

Guys will favour a side and the stance and technique for the O-Line does differ from side to side. Most players can adapt to the change but others can struggle.

If a team has a left handed quarterback as a starter then the tackle with the best pass pro would be at right tackle rather than left. An example of this is Hall of Fame tackle Anthony Munoz who while playing right tackle for Cincinnatti protected left handed QB Boomer Esiason's blindside.

You wouldnt see the line flipping sides if a backup came in during a game - left handed QBs are quite rare and you would probably only see an alignment change if the right handed starter was out for a few games.

Guys will favour a side and the stance and technique for the O-Line does differ from side to side. Most players can adapt to the change but others can struggle.

They don't change sides, you just need to invest in a very good right tackle to protect the blindside.

Like horrorshow said, Esiason was left handed, but he only came into the Bengals side in '84, Munoz was starting left tackle from 1980-93, so he had 4 seasons protecting Ken Anderson, who was right handed. He played left tackle his entire career though.

People here are generally right. The best example would be the 1988 San Francisco 49ers who, because of injuries and loss of form, alternated between the right-handed Joe Montana and the left-handed Steve Young throughout the year. Steve Wallace and Harris Barton remained the left and right tackles throughout the season with no attention paid to switching sides. Wallace did briefly play right tackle in 1990 with Barton switching to guard, but that was simply to accomodate Bubba Paris re-joining the starting lineup.

When Kenny Stabler was a Raider, Art Shell and Gene Upshaw were on the left side the entire time. While the Raiders had some pretty good right tackles (Bob Brown and John Vella), Shell and Upshaw were a class apart.